Title page for ETD etd-0711103-155908

Document Type thesis

Author Name Salehian, Armaghan

URN etd-0711103-155908

Title Identifying the Location of a Sudden Damage in Composite Laminates Using Wavelet Approach

Degree MS

Department Mechanical Engineering

Advisors
Zhikun Hou, Advisor
Mikhail Dimentberg, Committee Member
Joseph Rencis, Committee Member
John Sullivan, Graduate Committee Rep

Keywords
damage
composite
wavelet

Date of Presentation/Defense 2003-06-27

Availability unrestricted

Abstract
This study presents a general approach for an inverse problem to locate a sudden structural damage in a plate. The sudden damage is modeled as an impulse load and response data are collected at various sensor locations. In this simulation study the response data were generated by the commercial finite element code ANSYS for three square plates: one is an isotropic plate and made of aluminum and the others are two different composite plates made of graphite-epoxy. All plates are simply supported along all their edges. The responses of these plates to both narrow band and wide band loading were analyzed by a wavelet transform. The wavelet coefficient maps for each type of signal was utilized to estimate the shortest path arrival times of flexural waves resulted from the damage by locating the wavelet coefficient peak values of the response data. Using the dispersion relations of wave propagation based on the Mindlin’s plate theory, a set of nonlinear equations were derived to solve this inverse problem and the location of the applied load, which models a structural damage, was determined. The estimated locations for all different types of plates have shown an excellent agreement with the actual location of the impact loads applied.

Files
thesis.pdf

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Document Type	thesis
Author Name	Salehian, Armaghan
URN	etd-0711103-155908
Title	Identifying the Location of a Sudden Damage in Composite Laminates Using Wavelet Approach
Degree	MS
Department	Mechanical Engineering
Advisors	Zhikun Hou, Advisor Mikhail Dimentberg, Committee Member Joseph Rencis, Committee Member John Sullivan, Graduate Committee Rep
Keywords	damage composite wavelet
Date of Presentation/Defense	2003-06-27
Availability	unrestricted
Abstract This study presents a general approach for an inverse problem to locate a sudden structural damage in a plate. The sudden damage is modeled as an impulse load and response data are collected at various sensor locations. In this simulation study the response data were generated by the commercial finite element code ANSYS for three square plates: one is an isotropic plate and made of aluminum and the others are two different composite plates made of graphite-epoxy. All plates are simply supported along all their edges. The responses of these plates to both narrow band and wide band loading were analyzed by a wavelet transform. The wavelet coefficient maps for each type of signal was utilized to estimate the shortest path arrival times of flexural waves resulted from the damage by locating the wavelet coefficient peak values of the response data. Using the dispersion relations of wave propagation based on the Mindlin’s plate theory, a set of nonlinear equations were derived to solve this inverse problem and the location of the applied load, which models a structural damage, was determined. The estimated locations for all different types of plates have shown an excellent agreement with the actual location of the impact loads applied.
Files	thesis.pdf